1. Field of the Invention
This invention generally relates to a bicycle chain wheel structure. More specifically, the present invention relates to a bicycle chain wheel structure that is integrated with part of the bottom bracket structure.
2. Background Information
Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle to make the bicycle easier to assemble and more affordable to purchase.
One particular portion of a bicycle that has been extensively redesigned over the past years is the drive train of the bicycle. A bicycle drive train typically has a chain that interconnects one or more front chain wheels to one or more sprockets mounted on the rear wheel. The front chain wheels are mounted on the bicycle frame by a bottom bracket that has a crank arm axle that rotates relative to the bicycle frame. Each end of the crank arm axle has a crank arm fixed thereto for rotating the crank arm axle relative to the bicycle frame. The crank arms extend outwardly from the bottom bracket in opposite directions and have pedals attached to their free ends for supporting the rider's feet. The front chain wheels are typically attached to the right crank arm to rotate therewith. Rotation of the pedals by the rider causes the chain wheels to rotate which in turn moves the bicycle chain to rotate the rear sprockets, and thus, rotate the rear wheel of the bicycle. In certain crank arm designs, the front chain wheels are coupled directly to the crank arm by fastening finger portions. The fastening finger portions are coupled to the hub portion of the crank arm, and extend radially outwardly from the hub portion of the crank arm.
One problem with these types of drive trains is that they include numerous parts. Accordingly, the front chain wheel structure is often very complex structure, which can be time consuming to assembly. Thus, these conventional structures can result in the bicycle being more expensive due to the increase costs involved in manufacturing and assembling all of the individual parts.
Another problem with these types of drive trains is that the rider's clothing can either get caught in-between the chain and the chain wheels, or the rider's clothing can become dirty from contacting these chains. To overcome these problems, bicycle manufactures have provided a protective cover or guard for the driving sprocket of a bicycle. Usually, such covers or guards are separate members that are attached to the right crank arm or one of the chain wheels. For example, some protective covers or chain guards are fixed to the front chain wheel by bolts extending in a direction relatively parallel to the axis of rotation of the chain wheel. Many protective covers or chain guards are made of a thin metal material or some plastic material.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved bicycle chain wheel structure. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.